The present invention relates to a process monitor control system, and more particularly to a process monitor control system suitable for the control operation of a plant control device and monitoring of the operating condition of the control device.
A method of controlling and operating a process control device by use of a display unit with a touch sensor and a computer is disclosed in JP-A-60-54017, filed Sept. 2, 1983 by Tokyo Shibaura Electric Co., Ltd., JP-A-60-54018, filed Sept. 2, 1988 by Tokyo Shibaura Electric Co., Ltd. and JP-A-61-226801 filed Mar. 30, 1985 by Tokyo Shibaura Electric Co., Ltd. In the method of plant control disclosed in these patent specifications, a signal from a touch sensor or a touch screen is applied to a computer, and the result of the processing of the signal is used to send a control signal to a process control device.
On the other hand, a display unit is disclosed in JP-A-60-54019, filed Sept. 5, 1983 by Hitachi Ltd., JP-A-57-152011 filed Mar. 13, 1981 by Hokushin Electric Works, Ltd. and JP-A-50-25987 filed July 11, 1973 by Yokogawa Electric Works, Ltd. As disclosed in these patent specifications, a control screen for indicating the control data of a control device involved is displayed in combination on a screen indicating a specific pattern of the control device.
In the system of the related art mentioned above, a control device is actuated in immediate response to a single control command yet no means is incorporated for preventing a faulty operation. In the case where the touch screen is touched in error or where the control of the touch screen is faulty, an erroneous control signal may be undesirably issued to the plant. This system also lacks the consideration of parallel operation of a plurality of control devices, which are instead operable only one by one in series.
Further, a control screen indicating the control data is displayed in superimposed relations with a control device on the display screen at the time of giving an instruction. The operator, desiring to operate a control device hidden behind the control screen, is required to take the trouble of restoring the screen indicating the control device alone and then touch the control device to call the control screen for the particular control device.